Software licenses dictate the permissible uses of the corresponding software. The license may include a limitation of time, so that the software is useable only for a period of time, such as with so called “demo” licenses. This allows a developer to let potential customers see how the software performs so as to make a decision about purchasing a full version of the software, or a license that is not time restricted. Time based licenses can also be used with subscription software, where the user of the software pays periodically to keep the license valid so as to continue using the software.
A problem arises, however, with most computer or client devices that are used to execute and run the software because it is a simple task to reset the clock of the machine, or set it back so as to extend the period of time the software may be used. This is possible because, in their simplest form, the software simply checks the machine's clock when it is installed, and simply notes the time from the machine's clock every time it is invoked. If the prescribed period of time has elapsed, according to the clock, the software quits and ceases execution. More sophisticated license enforcement schemes include keeping track of the total time the software is active, and disallowing any further execution once a cumulative time period has been reached. However, this method can be overcome fairly easily as well.
Therefore there is a need for a method for enforcing a time limited software license. This is particularly true with less sophisticated machines, such as personal organizers and mobile communication devices such as cellular radiotelephones. Mobile communication devices have gained widespread popularity, and many are presently being offered with the ability to browse media content on the Internet, as well as to obtain software over the Internet. However, few have reliable means of tracking the date and time, and are largely dependent on the user correctly entering the time and date. Therefore there is a need for a method for enforcing a time limited software license in mobile communication devices.